The performance of some electronic devices can be improved by cooling them to cryogenic temperatures. Such cooling can be achieved by the use of a cryogenic fluid such as liquid or gaseous Nitrogen or Helium. For many cooling configurations an electronic device is brought into thermal contact with fluid held in a relatively small container. As the device is cooled, fluid is evaporated which must then be replenished from a remotely located reservoir. The fluid pressure in the container is generally low, typically atmospheric, whereas the pressure in the reservoir may be the same or higher. Conventional pumps are unable to efficiently provide the automatic, low volume, low pressure and low temperature operation required by such applications.